The bleed from Blood is Power does more damage and stacks twice compared to the signet's single stack. It also lasts 39s compared to 6.5s. There is also an overlap of time since BiP lasts 39s and has a 30s cooldown.... you will always have the bleed from it on the target.

I usually do BiP > Plague Signet > Grasping Dead > Enfeebling Blood > Mark of Blood > Dodge that procs Mark of Blood > Epidemic for a good damage rotation. Incredibly strong AoE as most targets get double stacks of bleeds around the initial target. Lacking for singe targets though. On paper the rotation sounds long but it takes around 3-4 seconds to do.